on Monday at work. In both cases you might be tired. Unless your job is highly unusual, you don't have physical pain you've already experienced and physical pain someone else is going to inflict on you in the next hour or so as part of your experience. You may have some doubts or anxiety, but you probably don't have someone that is highly skilled at what you do that is going to try to amplify your anxiety and doubts and use them against you.

There's a little "mob" mentality. When you see others around you expressing confidence and getting amped up, it rubs off and people feed off each other. It's not surprising that "rah rah" speeches work sometimes.